The invention to which this application relates is to provide improvements to a configuration of a cable, said cable formed by integrating a series of conductor sets or pairs passing therealong into a cable body and the cable provided for any suitable, conventional or specialist cable usage including data transmission, audio, video energy transmissions.
The Applicant, in their co-pending Application No. PCT/GB2003/001005, discloses cables for use in a variety of fields. The improvements relate to the configuration of conductors within each conductor set and also to the configuration of the conductor sets with respect to other conductor sets passing along the cable. As will be seen from the Applicant's co-pending application, significant improvements in terms of the consistency of each conductor set and the distance apart between adjacent conductor sets, provides improvements in Near End Cross Talk (NEXT), PSNEXT, PSFEXT, ELFEXT impedance performance and return loss for example. Furthermore, the degree of twist density between conductor pairs with respect to adjacent conductor sets, allows the ability to reduce, amongst other parameters, near end cross talk between the conductor pairs such that comparison of the improved cable as defined in the Applicant's co-pending application, with conventionally available Cat-5 Cat-6 or Cat-7 cables, provided remarkable and significant improvements in performance.
In this current application, the Applicant has identified further improvements to the configuration of conductors within cables and the formation of the cables themselves and preliminary results suggest that improvements in performance when compared with the conventional cables is again achieved. It is envisaged that these improvements, as herein defined, will allow the cable to be used in areas where other cables may not be of optimum suitability and to further provide improvements.
A further problem with the use of certain configurations of conventional cable and in particular materials used to encapsulate the conductors which pass along the cable, is that the material, when formed, can be relatively rigid. While this rigidity is of benefit in certain instances, where, for example, the cable is required to be installed in a relatively straight line, the rigidity can cause problems where the cable is required to be fitted around curves or bends and a further problem is that the cable can be difficult to store in an efficient manner.
Furthermore, problems can occur in the formation of cables housing a series of conductor sets, each of said sets having at least two conductors provided in a twisted orientation. Conventionally, when forming cables of this type, the conductors in each pair are requited to be produced in an exact symmetrical manner in terms of the twist and density of twist along the length of each of the conductor pairs. If the same are not provided in a symmetrical manner, then performance issues can arise in terms of impedance, capacitance, inductance, resistance and/or return loss.
Conventionally, to construct a typical high speed balanced data cable, an initial process is used which is called twinning. This is where two insulated conductors of required size are twisted together as shown in prior art FIG. A. Conventionally, the density of twists differs from conductor set to conductor set due to the close proximity of the conductor sets when the cable is formed. This density of twist and variation in the same is provided in an attempt to reduce or minimise cross-talk between each of the conductor pairs.
The twisting of these conductor sets must be extremely accurate as any fluctuations will cause inconsistency within the cable and thus cause degradation in performance and hence the associated equipment it services. Once the twisting has been performed, the conductor sets are then wound onto separate drums from which the conductor set is subsequently fed into cable forming apparatus which allows the extrusion of the cable and the location of the conductor sets with respect to each other in the cable. In order to do this, the drums are placed into a “payoff” section at the start of the extrusion process and are fed through a convergence eyelet which allows them to pass through a die head and hence form the cable by introducing a sheath which overlies the conductor sets and forms the outer surface of the cable. It is during this process that the arrangement of the conductor sets are most vulnerable to problems as the sets are drawn or pulled off the drums and, in order to do so, force must be applied. This force causes tension to the conductor sets which, as the conductor sets are held together by the introduction of the twist, can cause the deformation and/or unravelling of the twist of the conductor sets.